This application is a national stage of PCT International Application No. PCT/EP2008/010007, filed Nov. 26, 2008, which claims priority under 35 U.S.C. §119 to German Patent Application No. 10 2008 005 999.4, filed Jan. 25, 2008, the entire disclosure of which is herein expressly incorporated by reference.
The invention relates to a driver assistance system and a method for assisting the driver of a vehicle in maintaining a traffic lane limited by traffic lane markings.
German patent document DE 694 02 278 T2 discloses a method of this general type, in which the course of a traffic lane used by a vehicle is detected by detecting traffic lane markings limiting the lane, and a steering torque is exerted on a steering system of the vehicle if it approaches one of the traffic lane markings, thereby assisting the driver in maintaining the traffic lane. If the traffic lane marking is subsequently crossed, the driver is informed by a haptic and acoustic warning. The environment of the vehicle is additionally monitored for collision-endangering objects with this method, and a lateral movement of the vehicle is prevented or inhibited, if collision-endangering obstacles are detected by the monitoring.
International patent document WO 2006/081936 A1 discloses a method for supporting the driver of a vehicle in maintaining a lane, in which the prospective deviation of the vehicle position from a nominal lane determined by means of traffic lane markings is determined and a supporting steering torque is generated when exceeding certain deviation thresholds, which supports the driver when guiding the vehicle back into the nominal lane. The deviation thresholds can thereby be varied in dependence on objects, which are detected in the driving direction of the vehicle laterally of the traffic lane driven on by the driver.
One object of the invention is to provide a driver assistance system and method of the above-mentioned type, for helping the driver of a vehicle to maintain a lane, wherein the supporting measures on the side of the system take place in such a manner that they are perceived by the driver as adequate and not as disturbing.
This and other objects and advantages are achieved by the driver assistance system according to the invention, which comprises a traffic lane recognition device for detecting a traffic lane driven on by the vehicle by means of lane-limiting traffic lane markings, a warning device for outputting a lane abandoning warning to a driver of the vehicle when recognizing a lane abandoning tendency, an object recognition device for detecting lateral objects which are present next to the detected traffic lane and a control device for carrying out a course correcting actuating intervention. The traffic lane recognition device is set up to recognize, based on the type of the traffic lane markings, whether a traffic lane change by passing over the traffic lane marking is permissible or impermissible; and the control device is set up to trigger an actuating intervention subsequent to the output of the lane abandoning warning when such a lane change is impermissible, or when there is a danger of collision with a detected lateral object.
According to the invention, therefore, support is offered to the driver in several escalation steps: in a first escalation step, a lane abandoning warning referring to the lane abandoning tendency is output and in a subsequent second escalation step, a course correcting actuating intervention acting against the lane abandoning tendency is carried out. The second escalation step is thereby only activated under the condition that the abandoning of the traffic lane is impermissible or is dangerous due to a possible collision with lateral objects. This means, in situations, in which the passing over the traffic lane marking is permissible and also possible without danger, the second escalation step is not activated and the course correcting actuating intervention is thus not carried out. In these situations it is assumed that the driver will deliberately want to leave the traffic lane and will perceive an actuating intervention acting against the lane abandoning as an inappropriate and unexpected system action, which would lead to acceptance problems with frequent occurrence.
The object recognition is preferably set up in such a manner that it can also detect objects that are in front in addition to lateral objects, which objects that are in front are within the traffic lane in front of the vehicle, and the control device is advantageously set up in such a manner that it suppresses the actuating intervention, if an evaluation of the situation results in that the danger of the collision with a detected front object is present.
It can be prevented in this manner that an evasion maneuver carried out by the driver for passing around an obstacle which is present in the driving path of the vehicle is prevented or hampered by the actuating intervention that takes place on the system side. The driver can thus evade a front object recognized as an obstacle and can thereby leave the traffic lane without a counter-reaction on the system side, even if an abandoning of the traffic lane would be impermissible.
The traffic lane recognition device is preferably set up to judge the abandoning of the traffic lane as permissible if the traffic lane marking that is being passed over is a broken line, and to judge it as impermissible if the traffic lane marking being passed over is a continuous line.
The control device is preferably arranged to carry out the actuating intervention by individual braking of individual wheels of the vehicle.
In an advantageous arrangement of the driver assistance system, the warning device is set out to output the lane abandoning warning in the form of steering wheel vibrations to the driver.
In a further advantageous arrangement of the driver assistance system, the object recognition device is set up to recognize standing and moving objects outside the traffic lane.
The control device is preferably set up to suppress the actuating intervention with a permissible abandoning of the traffic lane, if an area that is sufficiently large for a lane change is present next to the traffic lane.
The traffic lane recognition device is preferably designed as a video-based lane recognition system.
The object recognition device is preferably arranged as a radar system.
With the method according to the invention for supporting the driver of a vehicle in maintaining a traffic lane limited by traffic lane markings, the traffic lane markings and the position of the vehicle within the traffic lane are detected, the environment of the vehicle is sensed for the presence of collision-endangering lateral objects next to the traffic lane, and when abandoning or an impending abandoning of the traffic lane, a lane abandoning warning is output to the driver, and a course correcting actuating intervention acting against the lane abandoning is carried out. The course correcting actuating intervention is carried out chronologically after the output of the lane abandoning warning; the abandoning of the traffic lane by means of the type of the traffic lane marking to be passed over hereby is furthermore judged to be permissible or impermissible; and the course correcting actuating intervention is suppressed if the abandoning of the traffic lane has been judged to be permissible and no collision-endangering lateral objects have been recognized next to the traffic lane.
The environment of the vehicle is further examined for the presence of collision-endangering front objects which are in front of the vehicle within the traffic lane, and the course correcting actuating intervention is suppressed if such a collision-endangering front object is recognized a present.
The actuating intervention is thus suppressed in situations, in which one can assume that the driver abandons the traffic lane deliberately, in order to evade a collision-endangering object in front recognized as an obstacle.
The abandoning of the traffic lane is thereby preferably judged to be permissible if the traffic lane marking to be passed over when abandoning the lane is a broken line.
The abandoning of the traffic lane is preferably judged to be impermissible if the traffic lane marking to be passed over when abandoning the lane is a continuous line.
In an advantageous further development of the method, it is estimated how high the danger of a collision of the vehicle with one of the collision-endangering lateral objects is when abandoning the lane, and the actuating intervention is carried out in dependence on the estimated height of the danger.
In an advantageous further development, the lane abandoning warning is output as a haptic warning.
In a further advantageous further development of the invention, the course correcting actuating intervention is carried out as a single wheel brake intervention.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.